1. Field
Exemplary embodiments relate to an optical mask, and more particularly, to an optical mask including a photothermal conversion layer, which may be patterned into high-absorption regions and low-absorption regions.
2. Discussion of the Background
A conventional organic electroluminescence (EL) device may include an anode electrode, a cathode electrode, and organic layers between the anode electrode and the cathode electrode. The organic layers may include a light-emitting layer (EML), as well as include a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), and an electron injection layer (EIL). The organic EL device may be classified as a high molecular organic EL device or a low molecular organic EL device depending upon one or more materials forming the organic layers.
A full-color organic EL device may utilize a patterned EML. If the organic EL device is a low molecular organic EL device, the EML may be patterned using a fine metal mask. On the other hand, if the organic EL device is a high molecular organic EL device, the EML may be patterned using an inkjet printing method or a laser-induced thermal imaging (LITI) method. The LITI method may enable finely patterned organic layers, as well as enable use of a dry etching method rather than a wet etching method, unlike the inkjet printing method.
Patterning of a high molecular organic layer using the LITI method at least utilizes a light source, an organic EL device substrate, i.e., a device substrate (or a target substrate to which an organic layer is to be transferred), and a transfer substrate. The transfer substrate typically includes a base film and a transfer layer including a photothermal conversion layer and an organic film. The photothermal conversion layer of the transfer substrate absorbs light emitted from the light source, and converts it into thermal energy. The organic film of the transfer layer may then be transferred onto the device substrate via the thermal energy. In this manner, an organic layer formed on the transfer substrate may be patterned onto the device substrate.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept, and, therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.